1. Field of the Invention
The present invention relates to miniature implantable pumps. More specifically, it relates to improved miniature implantable pumps which may be used as bio-compatible medical implants for controlling diseases such as glaucoma and for controlled delivery of drugs.
2. Description of the Prior Art
Mechanical and electro-mechanical medical implants are well known and, depending upon the type, have met with varying success rates. One problem with these devices is the lack of a reliable, long term power source. Ideally, the power source should last for the life of the implant, as many of these implants require invasive procedures both to install and maintain. Indeed, an external power source is virtually impossible in many situations.
One use for mechanical implants is the treatment of glaucoma. Glaucoma is a common eye disease which is caused by excessive ocular pressure in the anterior chamber of the eyeball. Many devices and techniques have been devised in order to control this pressure. The devices fall generally into two types; passive devices such as a simple tubular shunts or similar device which drains aqueous humor from the anterior chamber, and active devices which have means for controllably draining ocular pressure, the systems typically using check valves or similar mechanical devices. While these systems are somewhat effective, they all tend to suffer from the drawback in that they are unreliable or require frequent maintenance which always involves a fairly invasive procedure. Failure to properly maintain the devices can result in long term damage to the eye.
Recently, mechanical devices have been used in order to effect controlled delivery of drugs. These devices are almost all passive, with the exception of a few highly experimental devices such as nanobots. Mechanical devices, while possessing many advantages, are rarely used as the reliability of passive devices is already established, albeit with the aforementioned shortcomings.
U.S. Pat. No. 5,370,607 issued to Memmen discloses a glaucoma implant device which has a tubular shunt for draining fluid from the eye. By contrast, the present invention contemplates a controllable, self powered pumping mechanism for draining fluid from the eye to treat glaucoma.
U.S. Pat. No. 4,911,616 issued to Laumann, Jr. discloses a microminiature pump which may be used to administer medications in sensitive locations in the body such as the eye. The pump is programmable, but the patent does not disclose which aspects of the pump operation can be controlled. Also, the pump requires a separate power source. By contrast, the present invention contemplates a miniature pump and conduit assembly which may be used, among other things, to control glaucoma by controllably pumping fluid from the eye in accordance with sensed pressure conditions within the eye.
U.S. Pat. No. 5,062,841 issued to Siegel discloses an insulin pump which can be used to pump insulin directly into the bloodstream in response to blood glucose levels. By contrast, the present invention contemplates a self powered miniature pump which can be implanted into the tissue surrounding the eye and can controllably reduce ocular pressure.
U.S. Pat. No. 5,433,701 issued to Rubinstein discusses an active ocular pressure control device which includes a pump which is selectively operated in response to a control signal from a pressure sensor. However, no details as to the power source or structure of the pump, microprocessor, or pressure sensing means are disclosed.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
The present invention concerns self-powered, implantable, pressure adjustable mini-pump systems for intraocular pressure control for glaucoma patients as well as other medical applications requiring body fluid pressure, drainage control and drug delivery systems. These mini-pump systems include a primary mini-pump chamber whose anterior end is attached to an implantable intake conduit. In the case of an ocular pressure control device, the intake conduit is inserted into the anterior chamber of the eye. The device of the invention is further equipped with an adjustable variable flow valve or shunt in the form of a first cantilever slab, in combination with an anterior end one-way valve in the form of another cantilever slab. A mini-pump composed of a pair of oscillatory flexing miniature ionic polymer metal composite IPPC artificial muscle, is used to pump fluid or dispense medications. The posterior end of the mini-pump chamber is connected to a drainage conduit, via yet another one-way valve, to drain local bodily fluids out to a flat fan-shaped distribution plate. A key feature of the invention is a secondary power generation system in the form of either a much larger piece of IPPC artificial muscle which, in the case of glaucoma prevention systems, may be placed on the globe surface (sclera) of the eye and attached to and secured by the extraocular muscles of the eye. An alternative external power system includes a biocompatible induction coil with gold wire armature that can be transcutanously activated, adjusted, and computer-interrogated and controlled by a surgeon. The power generated in the larger IPPC artificial muscle by random eye muscle motion maybe used to power the mini-pump to automatically drain excess aqueous humor from the anterior chamber through the mini-pump chamber. Alternatively, the power generating artificial muscle is replaced by a power generation induction coil made with gold wires. The power generated by the induction coil transcutanously from outside of the eye by a microprocessor and computer-controlled power induction system can be used by both the patient and or the opthamologist/surgeon to continuously interrogate and monitor the intraocular pressure in the anterior chamber and to enable the mini-pump, to pump out excess aqueous humor from the pressurized anterior chamber of a glaucoma patient. If the pump is used to administer drugs, the artificial muscle may be used to derive power from local musculature, and information concerning the amount and time of dispensing, among other things, may be obtained. A pressure regulating system including a pressure sensor and pump controlling microprocessor may also be used with the inventive system.
A new class of ionic polymer metal composite (IPMC) artificial muscles has been developed at the University of New Mexico Artificial Muscles Research Institute (AMRI). IPMC micro-actuators and sensors have been designed, fabricated and successfully tested. These artificial muscles are made from ionic polymeric (polyelectrolyte) gels chemically treated with platinum (IPPC). They exhibit large motion sensing and actuation capabilities in a distributed manner. IPMCs are three-dimensional networks of cross-linked macromolecular polyelectrolytes with internal electrodes that swell, shrink, bend or generally deform in an electric field. Conversely, IPMCs are capable of generating an electric field or voltage as a result of being manipulated. Thus, direct computer control and monitoring of large expansions and contractions of ionic polymeric gel-noble metal composite muscles by means of voltage controller has been achieved. In fact, they require only a few volts for actuation. These muscles can be cut as small as needed and still preserve their functional properties. Accordingly, this technology is incorporated into the present invention as will be explained in more detail later.
Accordingly, it is a principal object of the invention to provide an implantable, self powered, miniature pump.
It is a major object of this invention to provide an implantable pump assembly and associated method for controlling intraocular pressure.
It is another object of the invention to provide such a pump assembly having an automatically controlled pumping rate.
It is still another object of the invention to provide an improved, biologically implantable pump assembly having a pumping rate which is controllable in response to sensed local pressure conditions.
It is another object of the invention to provide an implantable pump assembly which can derive electrical power from muscle movement.
It is another object of the invention to provide an implantable pump assembly which can administer drugs.
It is another object of the invention to provide a miniature pumping system for controlling ocular pressure having means to generate power from the movement of the ocular muscle.
It is another object of the invention to provide a miniature pumping system which can be interrogated electronically while remaining implanted in the body.
It is another object of the invention to provide an improved method and apparatus for controlling glaucoma including a micropump which is implanted into the anterior chamber of the eye.
It is another object of the invention to provide an improved method and apparatus for controlling glaucoma including a micropump where pump operation is controlled in accordance with the disease state of the optic nerve and the sensed ocular pressure.
It is yet another object of the invention to provide an improved, biologically implantable pump assembly having a draining tube with a relatively wide outlet end to disperse the outflow of fluid.
It is yet another object of the invention to provide an improved, biologically implantable pump assembly having constant flow therethrough to prevent occlusion of the drainage tube.
Finally, it is a general object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.